/*
* This code implements the MD5 message-digest algorithm.
* The algorithm is due to Ron Rivest.  This code was
* written by Colin Plumb in 1993, no copyright is claimed.
* This code is in the public domain; do with it what you wish.
*
* Equivalent code is available from RSA Data Security, Inc.
* This code has been tested against that, and is equivalent,
* except that you don't need to include two pages of legalese
* with every copy.
*
* To compute the message digest of a chunk of bytes, declare an
* MD5Context structure, pass it to MD5Init, call MD5Update as
* needed on buffers full of bytes, and then call MD5Final, which
* will fill a supplied 16-byte array with the digest.
*/
#include <string.h> /* for memcpy() */

/* 
   scsh specific changes by Martin Gasbichler:
   - inlined the header file
   - made all MD5 procedures static
   - define HIGHFIRST according to WORDS_BIGENDIAN
   - included scheme48.h
   - added the stub functions
*/

#include "sysdep.h"
#include "scheme48.h"

typedef unsigned long uint32;

struct MD5Context {
        uint32 buf[4];
        uint32 bits[2];
        unsigned char in[64];
};

static void MD5Init(struct MD5Context *context);
static void MD5Update(struct MD5Context *context, unsigned char const *buf,
	       unsigned len);
static void MD5Final(unsigned char digest[16], struct MD5Context *context);
static void MD5Transform(uint32 buf[4], uint32 const in[16]);

typedef struct MD5Context MD5_CTX;
#ifdef WORDS_BIGENDIAN 
#define HIGHFIRST
#endif

#ifndef HIGHFIRST
#define byteReverse(buf, len)	/* Nothing */
#else
static void byteReverse(unsigned char *buf, unsigned longs);

#ifndef ASM_MD5
/*
* Note: this code is harmless on little-endian machines.
*/
static void
byteReverse(unsigned char *buf, unsigned longs)
{
        uint32 t;
        do {
                t = (uint32) ((unsigned) buf[3] << 8 | buf[2]) << 16 |
                ((unsigned) buf[1] << 8 | buf[0]);
                *(uint32 *) buf = t;
                buf += 4;
        } while (--longs);
}
#endif
#endif

/*
* Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
* initialization constants.
*/
static void
MD5Init(struct MD5Context *ctx)
{
        ctx->buf[0] = 0x67452301;
        ctx->buf[1] = 0xefcdab89;
        ctx->buf[2] = 0x98badcfe;
        ctx->buf[3] = 0x10325476;

        ctx->bits[0] = 0;
        ctx->bits[1] = 0;
}

/*
* Update context to reflect the concatenation of another buffer full
* of bytes.
*/
static void
MD5Update(struct MD5Context *ctx, unsigned char const *buf, unsigned len)
{
        uint32 t;

        /* Update bitcount */

t = ctx->bits[0];
        if ((ctx->bits[0] = t + ((uint32) len << 3)) < t)
        ctx->bits[1]++;		/* Carry from low to high */
ctx->bits[1] += len >> 29;

        t = (t >> 3) & 0x3f;	/* Bytes already in shsInfo->data */

/* Handle any leading odd-sized chunks */

if (t) {
                unsigned char *p = (unsigned char *) ctx->in + t;

                t = 64 - t;
                if (len < t) {
                        memcpy(p, buf, len);
                        return;
                }
                memcpy(p, buf, t);
                byteReverse(ctx->in, 16);
                MD5Transform(ctx->buf, (uint32 *) ctx->in);
                buf += t;
                len -= t;
        }
        /* Process data in 64-byte chunks */

while (len >= 64) {
                memcpy(ctx->in, buf, 64);
                byteReverse(ctx->in, 16);
                MD5Transform(ctx->buf, (uint32 *) ctx->in);
                buf += 64;
                len -= 64;
        }

        /* Handle any remaining bytes of data. */

memcpy(ctx->in, buf, len);
}

/*
* Final wrapup - pad to 64-byte boundary with the bit pattern
* 1 0* (64-bit count of bits processed, MSB-first)
*/
static void
MD5Final(unsigned char digest[16], struct MD5Context *ctx)
{
        unsigned count;
        unsigned char *p;

        /* Compute number of bytes mod 64 */
count = (ctx->bits[0] >> 3) & 0x3F;

        /* Set the first char of padding to 0x80.  This is safe since there is
        always at least one byte free */
p = ctx->in + count;
        *p++ = 0x80;

        /* Bytes of padding needed to make 64 bytes */
count = 64 - 1 - count;

        /* Pad out to 56 mod 64 */
if (count < 8) {
                /* Two lots of padding:  Pad the first block to 64 bytes */
memset(p, 0, count);
                byteReverse(ctx->in, 16);
                MD5Transform(ctx->buf, (uint32 *) ctx->in);

                /* Now fill the next block with 56 bytes */
memset(ctx->in, 0, 56);
        } else {
                /* Pad block to 56 bytes */
memset(p, 0, count - 8);
        }
        byteReverse(ctx->in, 14);

        /* Append length in bits and transform */
((uint32 *) ctx->in)[14] = ctx->bits[0];
        ((uint32 *) ctx->in)[15] = ctx->bits[1];

        MD5Transform(ctx->buf, (uint32 *) ctx->in);
        byteReverse((unsigned char *) ctx->buf, 4);
        memcpy(digest, ctx->buf, 16);
        memset((char *) ctx, 0, sizeof(ctx));	/* In case it's sensitive */
}

#ifndef ASM_MD5

/* The four core functions - F1 is optimized somewhat */

/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

/* This is the central step in the MD5 algorithm. */
#define MD5STEP(f, w, x, y, z, data, s) \
( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )

/*
* The core of the MD5 algorithm, this alters an existing MD5 hash to
* reflect the addition of 16 longwords of new data.  MD5Update blocks
* the data and converts bytes into longwords for this routine.
*/
static void
MD5Transform(uint32 buf[4], uint32 const in[16])
{
        register uint32 a, b, c, d;

        a = buf[0];
        b = buf[1];
        c = buf[2];
        d = buf[3];

        MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
        MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
        MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
        MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
        MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
        MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
        MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
        MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
        MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
        MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
        MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
        MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
        MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
        MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
        MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
        MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

        MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
        MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
        MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
        MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
        MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
        MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
        MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
        MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
        MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
        MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
        MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
        MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
        MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
        MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
        MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
        MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

        MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
        MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
        MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
        MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
        MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
        MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
        MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
        MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
        MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
        MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
        MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
        MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
        MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
        MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
        MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
        MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);

        MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
        MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
        MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
        MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
        MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
        MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
        MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
        MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
        MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
        MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
        MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
        MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
        MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
        MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
        MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
        MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);

        buf[0] += a;
        buf[1] += b;
        buf[2] += c;
        buf[3] += d;
}

#endif

/*
 * S48 stub functions for the procedures above.
 * Added by Martin Gasbichler.
 *
 */

static s48_value make_MD5_CTX(void);
static MD5_CTX* extract_context(s48_value);
static s48_value MD5Init_stub(s48_value sch_context);
static s48_value MD5Update_stub (s48_value sch_context, s48_value input);
static s48_value MD5Final_stub (s48_value sch_context);


static s48_value make_MD5_CTX(void){
  return S48_MAKE_VALUE(MD5_CTX);
}

static MD5_CTX* extract_context(s48_value sch_context){
  return S48_EXTRACT_VALUE_POINTER (sch_context, MD5_CTX);
}

static s48_value MD5Init_stub(s48_value sch_context){
  MD5Init (extract_context (sch_context));
  return S48_UNSPECIFIC;
}

static s48_value MD5Update_stub (s48_value sch_context, s48_value input){
  MD5Update (extract_context (sch_context),
	     (unsigned char*) s48_extract_string (input),
	     S48_STRING_LENGTH (input));
  return S48_UNSPECIFIC;
}

static s48_value MD5Final_stub (s48_value sch_context){
  unsigned char digest[16];

  MD5Final (digest, extract_context (sch_context));
  return s48_enter_substring ((char*) digest, 16);
}


				
void s48_init_md5 (void){
  S48_EXPORT_FUNCTION (make_MD5_CTX);
  S48_EXPORT_FUNCTION (MD5Init_stub);
  S48_EXPORT_FUNCTION (MD5Update_stub);
  S48_EXPORT_FUNCTION (MD5Final_stub);
}
